Segment Information (Reconciliation of Federal Income Tax Expense (Benefit) From Segments to Consolidated) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	$ 257	$ (1,287)	$ 267
Annuities Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	187	198	261
Retirement Plan Services Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	28	50	43
Life Insurance Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	116	236	210
Group Protection Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	50	55	35
Other Operations [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(48)	(78)	(42)
Excluded Realized Gain (Loss) [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(61)	(220)	(241)
Gain (loss) on early extinguishment of debt, tax, reconciling item [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)		(2)
Reserve changes (net of related amortization) on business sold through reinsurance [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)			$ 1
Net Impact From Tax Cuts And Jobs Act [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	3	$ (1,526)
Acquisition And Integration Costs Related To Mergers And Acquisitions [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	$ (18)